Operation completion detection means

ABSTRACT

Operation completion detection circuitry for a vend system including a plurality of individually controllably operable motors for performing a given type of operation, comprising power leads, a vend control circuit portion operatively connected to complete a circuit across the power leads through a given motor from among the plurality of motors, a cam operated switch associated with each motor and connected in series circuit therewith, each of which switches includes a first pole and a second pole, connected in common, and a controllably movable switch contact which is normally in electrical contact with the first pole of the switch means and is responsive to operation of the motor with which such cam operated switch is associated to switchably cycle between such first and second poles during a complete operational cycle of the motor, and a detector circuit which includes a monitor portion thereof operatively connected in common circuit to all of the motors and their associated cam operated switches and in series circuit with each respective motor and its associated cam operated switch, which detector circuit is responsive to operation of the movable switch contact of any of the cam operated switches to produce and to provide to the vend control circuit portion a home detection signal when the motor associated with such cam operated switch has operated sufficiently to cause the movable switch contact of such switch to complete a movement cycle and to return to electrical contact with the first pole of such switch.

BACKGROUND OF THE INVENTION

The present invention relates to operation completion detection meansfor vending systems, especially for vending systems that include aplurality of individually actuatable vend delivery motors for vending avariety of different products.

Many existing vending systems have been designed to utilize controllablyactuatable motors or other actuators to effect certain operations. Byway of example, vend delivery motors may be employed to effect thevending under appropriate conditions of a product or products selectedby a customer, coin payout motors may be employed to effect distributionof overdeposited credit amounts back to a customer, and other motors maybe employed for other purposes related to the vending system operation,such as movement of a cup into which a liquid is to be dispensed intoposition or the controlled opening and closing of a dispensing valve.Vending systems that utilize such controllably actuatable motorsgenerally require that each motor, when controllably actuated,thereafter remain energized to operate for some sufficiently long enoughperiod that the particular operation associated therewith will becompleted as a result of such motor operation. Such period may bereferred to as an operation cycle. In most cases, the operation cycle isfunctionally related to the operation of the motor and can be readilydetermined by monitoring the shaft rotation of the motor during theperiod of motor energization. As a result, it has been found that, bymonitoring the shaft rotation of the selected motor, it is possible todetermine when the motor has operated sufficiently under normalcircumstances to cause the particular operation associated therewith tobe completed and to permit the motor to be de-energized.

Typically, during an operation cycle of a vend delivery motor a varietyof different events must occur in proper sequence for a product deliveryto occur. Such events often involve several mechanical movements, all ormost of which are controlled either directly or indirectly by operationof the appropriate vend delivery motor. In many instances, mechanical orelectromechanical devices, such as cams and cam operated switches, aremounted upon or are associated with the output shaft of such motor toeffect such events in their proper sequence. However, as a consequencethereof, it is important that the motor be in a proper initial state atthe time it is first actuated to ensure that the desired sequence ofoperations will actually occur in the proper sequence, especially sincethe mechanical movements of a vend delivery operation are ofteninterdependent to some extent. In many instances, if a particularmechanical movement required in a vend delivery operation is notperformed, subsequent mechanical movements in a sequence of operationmay not be effective to cause a product to be delivered. Consequently,it is recognized that the de-energization of a vend delivery motor mustgenerally be effected at such a time and in such a manner at theconclusion of a delivery cycle so that such motor will be in a properinitial state for a subsequent vend delivery operation.

It is well known that a cam on the output shaft of a motor may beutilized not only to control the various mechanical movements necessaryto effect a particular operation, such as to provide a product to thecustomer, but also to provide indications that the ouput shaft of themotor has rotated to such an extent that normal product delivery shouldhave occurred and/or that the motor is in a proper state such thatde-energization of the motor will leave it in a proper initial state forsubsequent vend operations. As has long been recognized, a motor cantherefore be provided with a cam on its output shaft, which cam maycontrol the position of a cam operated switch that is wired in a circuitthat is operatively connected to or monitored by the vend control meansof the vending system.

Many known vending systems have made use of such types of circuitswherein cam operated switches form no part of the motor driving circuitbut are disposed in separate sensing circuits wherein their operation isdetectable by the vend control means of the vending system to effectother operations related to the vending operation and/or to cause themotor driving such cam to be de-energized. For example, U.S. Pat. Nos.3,307,671; 3,508,636; 3,589,492; 3,687,255; 4,008,792; and 4,105,867,all of which are assigned to a subsidiary of Applicant's assignee, alldisclose the use of a coin payout motor which has a cam operated switchassociated therewith that is operable to effect a change in status of aseparate sensing circuit, which change in status is detectable by thevend control means of the vending system and provides an indicationthereto that the payout motor has operated sufficiently such thatfurther operations relative to coin payback operations should be taken.In addition, U.S. Pat. Nos. 3,894,220 and 4,008,972, both of which arelikewise assigned to the same subsidiary of Applicant's assignee,disclose the use of cam operated switches associated with vend motors toeffect changes in status of separate sensing circuits, which changes instatus are detectable by the vend control means of the vending systemsto effect de-energization of the vend motors under appropriateconditions.

It will be appreciated that, as the number of individually selectableand actuatable motors for performing a given type of operationincreases, so does the number of cam operated switches associatedtherewith. Quite obviously, if a separate sensing circuit were utilizedfor each cam operated switch, a large amount of replicative circuitrywould be required for vending systems that employ a plurality of vendmotors, especially for certain vending systems that now employ thirty orsixty or even more vend motors. To avoid the necessity of providing suchreplicative circuitry, many known systems that employ a plurality ofvend motors, such as those disclosed in U.S. Pat. Nos. 3,894,220 and4,008,972, use a daisy chain wiring technique with the plurality of camoperated switches. While such types of arrangements have generally beenfound to achieve desired results, they do have certain disadvantagesassociated with them, as well. A separate sensing circuit, with all thewiring attendant thereto, is still required for such systems, and,because of the daisy chaining required, the failure of a single motor,such as by hanging up partway through its operation cycle, may besufficient in some circumstances to totally disable the sensing circuitand to thereby render the entire vending system inoperable.

Other known systems have also been developed wherein the cam operatedswitches associated with the particular motors have been so utilizedthat, when the movable switch contact of the cam operated switch meansassociated with a given motor is in one position, such cam operatedswitch comprises a portion of a motor hold circuit to ensure that, undercertain conditions, once motor operation has been initiated by somemeans, motor energization will be continued for some period of time asdetermined by the controlled switching action of the associated camoperated switch. For example, U.S. Pat. No. 3,307,671 discloses the useof a cam operated switch associated with a refund motor in a motor holdcircuit for such motor, the purpose of which is to enable the motor tocomplete an operating cycle and stop at a predetermined position. As thenumber of motors increases in a vending system, however, so does theamount of replicative circuitry required to provide motor hold circuitryfor each motor. U.S. Pat. No. 4,034,839, assigned to a subsidiary ofApplicant's assignee, discloses one vending system in which a pluralityof cam operated switches are employed in a daisy chain arrangement inmotor hold circuitry to ensure that a given motor will remain energizedto complete an operation even if the motor selection switch which wasrequired to be actuated to initiate motor energization is de-actuatedprior to completion of motor operation. U.S. Pat. No. 4,478,353,assigned to the same subsidiary of Applicant's assignee, discloses adifferent system in which cam operated switches are employed with soldout switches associated with the vend motors to establish motor holdcircuits to maintain energization of a given motor so that it cancomplete its operation cycle even if the product being vended is thelast product and its delivery would normally cause a transfer of a soldout switch to prevent motor energization. U.S. Pat. No. 4,526,263, alsoassigned to the same subsidiary of Applicant's assignee, discloses asystem in which a plurality of cam operated switches are so connectedthat the movable contact of each such switch in one position comprises aportion of a motor hold circuit for the motor with which it isassociated and in another position comprises a portion of a separatesensing circuit similar in many respects to the types disclosed in U.S.Pat. Nos. 3,894,220 and 4,008,792.

To avoid the disadvantages associated with large amounts of replicativecircuitry and/or daisy chaining arrangements of the cam operatedswitches, other systems have been developed wherein a cam operatedswitch associated with a given motor is connected in a series circuitwith an impedance element, such as a resistor or capacitor, across,i.e., in parallel circuit with, such given motor. U.S. Pat. No.4,458,187 discloses various embodiments of such types of systems. Whilesuch types of systems avoid some of the disadvantages attendant to daisychain arrangements of cam operated switches and limit to some extent theamount of replicative circuitry that is required when a plurality ofmotors and associated cam operated switches are employed, because of theparallel circuitry asssociated with each motor, they still requirefairly substantial numbers of the various components that are includedin the circuit portions parallel to each of the motors and they may alsorequire greater power, especially upon initialization of energization,to drive the selected motor than would be the case if such replicativecircuitry for each motor were not present or required. Furthermore, withsome types of such systems that include such parallel circuitry andemploy AC signals to sense the status of the motors, several of whichare disclosed in U.S. Pat. No. 4,458,187, additional circuitry, with theconsequent additional costs that are associated therewith, may berequired. By way of example, with some of the known embodiments thatemploy AC signals for sensing motor status, additional AC oscillatorsand band pass filters are required in addition to a plurality ofcapacitors for connection in series circuit with the cam operatedswitches across the motors and a relatively sophisticated detectioncircuit.

SUMMARY OF THE INVENTION

The present invention avoids many of the disadvantages of the variousvend systems that have been discussed hereinbefore, and does so byeliminating the need for separate sensing circuits for each motor, fordaisy chain harnesses in sensing circuits, and for replicative circuitryemploying a plurality of impedance elements and, in some instances,additional frequency oscillators and/br band pass filters. With thepresent invention, only a single detection circuit means need beemployed and the amount of replicative circuitry required for aplurality of motors can be greatly minimized.

In its presently preferred form, the subject invention includes a vendcontrol means operatively connected to control operation of one or moreof a plurality of individually controllably actuatable motors operablefor performing a given type of operation. Each motor has a cam operatedswitch means associated therewith and connected in series circuit withthe motor, which switch means includes a first pole and a second pole,connected in common, and a controllably movable switch contact which isnormally in electrical contact with its first pole and is responsive tooperation of the motor with which such cam operated switch is associatedto switchably cycle between such first and second poles during acomplete operational cycle of the motor. A detector circuit means isprovided with a monitor portion thereof operatively connected in commoncircuit to all of the motors and their associated cam operated switchmeans and in series circuit with each respective motor and itsassociated cam operated switch means, which detector circuit means isresponsive to operation of the movable switch contact of any of the camoperated switch means to produce and to provide to the vend controlmeans a home detection signal when the motor associated with such camoperated switch means has operated sufficiently to cause the movableswitch contact to complete a movement cycle and to return to electricalcontact with the first pole.

In operation, the vend control means, upon a determination that asufficient amount of credit has been deposited by a customer for theitem selection made by him, effects establishment of a power drivecircuit to a given motor and its associated cam operated switch means tothereby complete a motor driving circuit through the given motor, itsassociated cam operated switch means, and the monitor portion of thedetector circuit means. The motor driving circuit for such given motorinitially comprises a first power circuit through the given motor andthrough the movable contact and the first pole of the cam operatedswitch means associated therewith. The completion of such motor drivingcircuit initiates operation of and the commencement of an operationalcycle of such given motor. The operation of such given motor thereaftereffects switchable movement of the movable switch contact of theassociated cam operated switch means from its first pole to its secondpole to break the first power circuit and to establish a second powercircuit through such given motor and through the movable contact andsecond pole of the associated cam operated switch means, upon whichoccurrence the motor driving circuit will then comprise the second powercircuit. Further operation of the given motor effects switchablemovement of the movable switch contact from the second pole back to thefirst pole to break the second power circuit and to re-establish thefirst power circuit through such given motor and through the movablecontact and first pole of the cam operated switch means associatedtherewith, whereupon the motor driving circuit again comprises the firstpower circuit. The switchable movement of the movable contact from itssecond pole to its first pole momentarily interrupts the motor drivingcircuit through the given motor and its associated cam operated switchmeans. This momentary interruption upon the return movement of themovable contact from the second pole to the first pole is detectable bythe detector circuit means, which detector circuit means produces andprovides to the vend control means a home detection signal. The vendcontrol means is thereupon responsive to such home detection signal toeffect disestablishment of the power drive circuit to the operatingmotor and its associated cam operated switch means, as a consequence ofwhich such motor will thereupon cease to operate.

In light of what has been discussed hereinabove, it will be appreciatedthat a principal object of the present invention is to provide animproved operation completion detection means.

Another object of the present invention is to provide an operationcompletion detection means that minimizes the amount of replicativecircuitry and circuit elements required.

A further object of the present invention is to provide a vending systemwith a motor operation completion means that alleviates the need toprovide high initial current to start a motor operation.

An additional object of the present invention is to provide an operationcompletion detection means that eliminates any need for daisy chainharnessing of cam operated switches for motor operation completiondetection purposes.

A still further object of the present invention is to provide anoperation completion detection means which has a high immunity tocircuit noise.

These and other objects and advantages of the present invention willbecome apparent after considering the following detailed specificationin conjunction with the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one embodiment of the operation completiondetection means of the present invention as incorporated into a singleprice vending system;

FIG. 2 is a block diagram of another embodiment of the present inventionas incorporated into a different single price vending system;

FIG. 3 is a block diagram of a further embodiment as incorporated into avending system capable of vending different products at differentprices.

FIG. 4 is a block diagram of an embodiment as incorporated into amulti-price vending system that utilizes X,Y motor matrix drives;

FIG. 5 is a partial circuit diagram depicting in greater detail onepossible construction of the X and Y drives depicted in FIG. 4; and

FIG. 6 is a circuit diagram depicting one possible embodiment of thedetector circuit means of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings more particularly by reference numbers,wherein like numbers refer to like components, number 10 in FIG. 1identifies a vend system employing operation completion detectioncircuitry in accordance with the present invention. The vend systemdepicted in FIG. 1 is a single price vend system that includes powerleads PL1 and PL2 which are operatively connected and/or connectable toa plurality of individually controllably actuatable motors 14a-14cthrough vend control means 12 and detector circuit means 24. Each motor14a-14c has associated therewith a respective cam operated switch means16a-16c connected in series circuit with the motor, each of which switchmeans 16a-16c includes a respective first pole 18a-18c and a respectivesecond pole 20a-20c, which first and second poles are connected incommon, and a respective controllably movable switch contact 22a-22cwhich is normally in electrical contact with its respective first pole18a-18c and is responsive to operation of the motor with which such camoperated switch means is associated to switchably cycle between thefirst pole of its respective switch means and the second pole thereofduring a complete operational cycle of the motor.

Detector circuit means 24 is connected between vend control means 12 andPL2 such that a monitor portion thereof is operatively connected incommon circuit to all of motors 14a-14c and their associated camoperated switch means 16a-16c via common lead 25 and in series circuitwith each respective motor and its associated cam operated switch meansvia lead 25 and respective leads 26a-26c. As will be apparent from thatwhich follows, such detector circuit means is responsive to themomentary circuit interruption effected by movement of a respectivemovable switch contact 22a-22c from its respective associated secondpole 20a-20c to its respective associated first pole 18a-18c to produceand provide a home detection signal to vend control means 12 via lead27.

The vend control means 12 as depicted in FIG. 1 may be considered toinclude a controller means 36 which functions to produce controlinformation signals, including vend authorization signals, overdata/control path 38 to a motor control means 40. As will be apparent tothose skilled in the art, such controller means 36 may take many forms,and many known controller means could be readily employed in the systemof FIG. 1. Motor control means 40 is shown as including a gating means42 connected to receive a vend authorization signal from controllermeans 36, which gating means is operable, as symbolically illustrated byswitch element 44, to effect an electrical communication from power leadPL1 to selection means 46 and then through an actuated selection switch48a-48c of selection means 46 to the respective motor 14a-14c associatedwith the actuated selection switch 48a-48c via a respective lead50a-50c.

In operation, when a credit entry at least equal to the vend price isdeposited by the customer and one of the selection switches 48a-48c ofselection means 46 is actuated, as for example, switch 48a, gating means42 operates in response to a vend authorization signal from controllermeans 36 to establish a power drive circuit to motor 14a and itsassociated cam operated switch means 16a to thereby complete a motordriving circuit from power lead PL1 through such motor, its associatedcam operated switch means, and detector circuit means 24 to power leadPL2. Such motor driving circuit initially comprises a first powercircuit through the motor 14a and through the movable contact 22a andthe first pole 18a of cam operated switch means 16a. The completion ofsuch motor driving circuit initiates operation of and the commencementof an operational cycle of motor 14a. The operation of such motorthereafter effects switchable movement of the movable switch contact 22aof the cam operated switch means 16a from its first pole 18a to itssecond pole 20a to break the first power circuit through the motor andto establish a second power circuit through such motor 14a and throughthe movable contact 22a and second pole 20a of the associated camoperated switch means 16a, upon which occurrence the motor drivingcircuit then comprises the second power circuit. Further operation ofmotor 14a thereafter effects switchable movement of the movable switchcontact 22a from the second pole 20a back to the first pole 18a to breakthe second power circuit and to re-establish the first power circuitthrough such given motor 14a and through the movable contact 22a andfirst pole 18a of the cam operated switch means 16a associatedtherewith, whereupon the motor driving circuit again comprises the firstpower circuit.

It will be appreciated that the cam operated switch means employed withthe present invention are preferably selected to be of a "snap-action"type to ensure that the movable contacts will not become hung up betweenthe first and second poles of the switch means, thereby interrupting themotor drive circuit for an extended period and causing the motor tocease operation. So long as the motors and cam operated switch means areso matched with one another that the movable contact of the cam operatedswitch means will be carried from one pole to the other pole of suchswitch means with only a momentary interruption of power to the motor,the motor and its associated cam operated switch means should operateadequately and in the manner intended with respect to the presentinvention.

In light of the foregoing, it will thus be apparent that the movement ofthe movable contact 22a from its second pole 20a to its first pole 18aduring the operation cycle of motor 14a effects an interruption in themotor driving circuit through such motor and its associated cam operatedswitch 16a, but only a momentary interruption. Such momentaryinterruption upon the movement of the movable contact 22a from thesecond pole 20a to the first pole 18a is detectable by detector circuitmeans 24, which means is responsive thereto to produce a home detectionsignal on lead 27.

Controller means 36 of vend control means 12 is operatively connected toreceive such home detection signal and, in response thereto, to effectdisestablishment of the power drive circuit to motor 14a and itsassociated cam operated switch means 16a, such as by causing switchelement 44 of gating means 42 to open. As a consequence of suchdisestablishment of the power drive circuit thereto motor 14a will thencease to operate and the movable contact 22a will remain in contact withfirst pole 18a, pending re-energization of such motor during asubsequent vend operation.

From what has been discussed hereinabove, it will be readily understoodthat the other motors and their respective cam operated switch meansoperate in similar manner to that already described with respect tomotor 14a and its associated cam operated switch means 16a. Accordingly,the operation of such other motors and cam operated switches will bereadily understood by those skilled in the art without need of furtherexplanation.

Turning next to FIG. 2, it will be readily apparent that such figuredepicts another single price vend system, similar in many respects tothat of FIG. 1, but employing a differently constructed selection means46' connected at a different location in the power drive circuit to themotors 14a-14b. Such differences in construction and circuit connectionare readily apparent from a comparison of FIGS. 1 and 2 and will bereadily understood by those skilled in the art. As is the case with thesystem of FIG. 1, no power drive circuit to a motor 14a-14b of thesystem of FIG. 2 will be established until both a vend authorizationsignal is provided to gating means 42 to effect the operation thereofand one of the selection switches 48a' or 48b' is actuated. At suchtime, a power drive circuit will then be completed to the motorassociated with the actuated selection switch, and operation of suchmotor and of the operation completion detection circuitry willthereafter proceed in the manner described with respect to the system ofFIG. 1.

FIG. 3 depicts a vend system capable of vending different products atdifferent vend prices. Such system is similar in many respects to thesystems of FIGS. 1 and 2, but in the FIG. 3 embodiment selection means46", which may take many forms, is connected via a data/control path 52to controller means 36 such that, when a vend selection is made byoperation of the selection means 46" selection information is providedto controller means 36, as a consequence of which a vend price isestablished for the particular vend selection made. If the customer hasdeposited a sufficient amount of credit for the particular vendselection made, an appropriate vend authorization signal will beprovided by controller means 36 via data/control path 38 to gating means42 of motor control means 40. In the embodiment of FIG. 3, gating means42 is depicted including NPN transistors 64a and 64b, which transistorsare so connected that their collectors 68a and 68b are tied together andconnected via lead 70 to power lead PL1, their bases 72a and 72b areoperatively connected to receive different respective vend authorizationsignals produced by controller means 36 and provided over data/controlpath 38, and their emitters 74a and 74b are operatively connected tovend motors 14a and 14b, respectively. When a sufficient amount ofcredit has been entered for a particular vend selection, a vendauthorization signal is provided to the base of the appropriatetransistor to thereby gate such transistor ON and thus complete a powerdrive circuit from power leads PL1 and PL2 to the particular vend motor14a or 14b associated with the vend selection made. The energized motorand the operation completion detection means of the system of FIG. 3will thereafter operate in the fashion previously described with respectto the system of FIG. 1.

It will be understood by those skilled in the art that many differenttypes of selection means and gating means may be employed with thepresent invention. FIG. 4 depicts another multi-price vend system thatemploys operation detection completion means according to the presentinvention, but wherein the selection means 46" is constructed to includea plurality of switches 80a-80d, each of which has one side tied toground and the other side operatively connected via data/control path 52to controller means 36 such that actuation of any selection switch willcause a corresponding vend selection signal to be provided to controllermeans 36 to establish a vend price for the particular vend selectionmade. If an amount of credit at least equal to the established vendprice has been entered into the system by the customer, controller means36 will then produce an appropriate signal or signals over data/controlpath 38 to cause motor control means 40 to effect completion of a powerdrive circuit from power leads PL1 and PL2 to the appropriate vend motor14a-14d associated with the vend selection made. It will be appreciatedthat, in the FIG. 4 system embodiment, motors 14a-14d are connected in amatrix format and gating means 42 includes a motor matrix control meansthat corresponds generally to the motor matrix control means disclosedin U.S. Pat. No. 4,284,208, which patent is assigned to a subsidiary ofApplicant's assignee. In accordance with the teachings of such notedpatent, controller means 36 provides over data/control path 38, when avend authorization condition arises, X,Y drive information to X drive 82and Y drive 84, which drives operate in response to such driveinformation to effect the operative communication of PL1 through X drive82 to an appropriate one of the X drive leads 88-92 and the operativecommunication of power lead PL2 through detector circuit means 24 and Ydrive 84 to an appropriate one of the Y drive leads 94-98, as aconsequence of which a power drive circuit is established from the powerleads to the particular motor 14a-14d corresponding to the vendselection made.

In operation, if selection switch 80a is actuated and an amount ofcredit at least equal to the vend price for the particular productassociated with such selection switch has been entered by the customer,controller means 36 will provide X,Y drive information over data/controlpath 38 to X drive 82 and Y drive 84. In response thereto, X drive 82will gate power lead PL1 to X drive output 88 and Y drive 84 will gatelead 25 to Y drive lead 94, as a consequence of which a motor drivecircuit will be established from X drive lead 88 through motor 14a andcam operated switch means 16a to Y drive lead 94. Once motor 14a hasbeen energized, such motor and the operation completion means will thenoperate in a manner similar to that previously described with respect tothe system of FIG. 1 so as to produce a home detection signal on lead27. Controller means 36 will respond to such home detection signal andcease production of the X,Y drive information on data/control path 38,as a consequence of which both the gating of power lead PL1 to X drivelead 88 and the gating of lead 25 to Y drive lead 94 will be terminated.

Those skilled in the art will recognize that the selection means and theX and Y drives employed in various embodiments may take many forms. Byway of example, the selection means could, in addition to the formsdescribed hereinbefore, also take the form of a numeric keyboardrequiring entry therefrom of one or more numbers to identify aparticular product to be vended and the vend motor associated therewith.The X and Y drives may similarly take many forms, including theparticular form depicted in FIG. 5. In FIG. 5, X drive 82 is shownincluding a plurality of NPN transistors 100-104, all of which havetheir collectors tied together and connected via lead 106 to power leadPL1. The emitters 110-114 of transistors 100-104 are connected,respectively, to X drive leads 88-92, and the bases 120-124 of suchtransistors are connected to receive respective X drive signals providedfrom controller means 36 over data/control path 38. In similar fashion,Y drive 84 is shown including a plurality of NPN transistors 130-134,all of which have their emitters tied together and connected via lead 25and detector circuit means 24 to power lead PL2. The collectors 140-144of such transistors are connected, respectively, to Y drive leads 94-98,and the bases 150-154 thereof are connected to receive respective Ydrive signals provided from controller means 36 over data/control path38. When an X drive signal is provided from controller means 36 andapplied to base 120 of transistor 100 and a Y drive signal is providedfrom control means 36 and applied to base 150 of transistor 130, both ofsuch transistors are gated ON to establish a power drive circuit tomotor 14a, such as has been discussed previously with respect to FIG. 4,as will be readily understood by those skilled in the art, especiallyafter a review of noted U.S. Pat. No. 4,284,208.

It will also be appreciated that the detector circuit means 24 of thepresent invention, the operation of which has been describedhereinbefore in rather general terms, may take many forms. FIG. 6depicts a detailed embodiment of one relatively simple detector circuitmeans 24 that could be employed with the present invention. The detectorcircuit means, as shown, includes resistor 160, one side of which isconnected both to lead 25 and to a monitor lead 162, and the other sideof which is connected through node 164 to power lead PL2. Monitor lead162 is connected to the negative (-) input 166 of comparison means 168,which preferably is a voltage comparator such as might be found on anLM339 chip, the positive (+) input 170 of which comparison means 168 isconnected to node 172 of a voltage divider network 173 that includesresistor 174, node 172, and resistor 176 connected in series circuitbetween a positive voltage source and node 164, which node isoperatively connected to power lead PL2. The output 180 of suchcomparison means 168, which output 180 is shown connected through node182 to signal generation means 184, is normally maintained HI by apull-up circuit 185 that includes resistor 186, node 182, and capacitor188 connected in series between a positive voltage source and ground.

In practice, comparison means 168 functions in such a manner thatwhenever the voltage level present at the negative input is greater thanthe voltage level present at the positive input, a logical LO outputresults. When the voltage level present at the negative input is lessthan the voltage level present at the positive input, a logical HI ispresent at the output.

It will be readily understood by those skilled in the art that thecomponents of the voltage divider network 173 connected to positive (+)input 170 of comparison means 168 can be easily varied to establish adesired voltage level at the positive input 170. For the purposes oflater reference herein the voltage established at such input terminal bymeans of the divider network will hereinafter be referred to as thereference point voltage, which voltage is selected to be less than thevoltage drop across resistor 160 when a motor drive circuit isestablished through a given motor.

In operation, prior to the establishment of a motor drive circuitthrough a given motor, no circuit will be completed through resistor 160and the reference point voltage will therefore be greater than thevoltage drop across resistor 160, as a consequence of which output 180of comparison means 168 will therefore be held HI by the pull-up circuit185. Thereafter, when a motor drive circuit is subsequently establishedthrough a given motor, the voltage drop across resistor 160 will exceedthe reference point voltage and the output 180 of comparison means 168will be driven LO and will so remain until a momentary interruption ofthe motor drive circuit occurs due to the movement of the movablecontact of the cam operated switch means associated with the energizedmotor from its first pole to its second pole. Upon such momentarycircuit interruption the reference point voltage will briefly exceed thevoltage drop across resistor 160 and the output 180 will therefore bepulled back HI for a brief period until the motor drive circuit isre-established as the movable contact completes its movement intocontact with the second pole of the cam operated switch means, at whichtime the output 180 will again be driven LO. As the energized motorcontinues to operate the movable contact of the associated cam operatedswitch means will thereafter be caused to move from the second pole backto the first pole, as a consequence of which the output 180 of thecomparison will again be momentarily pulled HI during the interruptionof the motor drive circuit.

From the foregoing, it will be appreciated that, with the comparisonmeans depicted in FIG. 6, two positive going signals will be produced atoutput 180 of comparison means 168 during each complete cycle of a givenenergized motor. However, in many instances it is desired to provide tovend control means 12 only a single signal which is intended torepresent detection of the return of such energized motor to a homeposition. Signal generation means 184 is therefore provided in the FIG.6 embodiment to receive the two positive going signals produced at theoutput 180 of comparison means 168 during a motor operation cycle, andto be responsive thereto to produce a home detection signal on lead 27only upon the occurrence of such second positive going signal, whichsignal is produced at output 180 of comparison means 168 when themovable contact of the cam operated switch means associated with theenergized motor returns from its second pole to its first pole. Manydifferent means and circuits could be employed to accomplish suchpurpose, one of which is depicted in greater detail in FIG. 6.

The signal generation means of FIG. 6 is depicted as including a D typeflip-flop 190, the C (clock) input 192 of which is connected throughnode 182 to output 180 of comparison means 168 to receive the signalsproduced thereat, and the Q output 196 of which is connected to lead 27and also back to the D (data) input 194 of such flip-flop. If theflip-flop is initially in a reset state, the first positive going signalat output 180 will clock the flip-flop causing it to set and the secondpositive going signal output 180 will clock the flip-flop causing it toreset. In accordance therewith, a HI signal will be produced on lead 27only when the flip-flop is reset in response to the momentaryinterruption of the motor drive circuit occasioned by the movement ofthe movable contact of the cam operated switch means from its secondpole to its first pole.

It should also be appreciated that signal generation means 184 need notbe employed with all vend systems. Some vend systems, especially thosethat include microprocessors as part of their controller means, may beso constructed or programmed to be directly responsive only to everysecond signal produced by a comparison means such as comparison means168. Such systems would therefore not require a signal producing meanssuch as signal producing means 184. Consequently, whether or notmultiple signals are produced by the detector circuit means required bythe present invention will be determined by the particular vend controlmeans utilized in any vend system. In any event, though, the homedetection signal provided to the vend control means will be that signalproduced by the detector circuit means in response to the movement ofthe movable contact of the cam operated switch means associated with theparticular motor energized from its second pole back to its first pole.

It should be noted that, although the subject invention has beendiscussed and described with reference to a plurality of vend motors, itmay be employed equally as well with any plurality of motors that areselectively individually actuatable to perform a given type ofoperation.

Thus, there has been shown and described a novel operation completiondetection means which fulfills the various objects and advantages soughttherefor. It will be apparent to those skilled in the art, however, thatmany changes, modifications, variations, and other uses and applicationsof the subject means are possible, and all such changes, modifications,variations, and other uses and applications which do not depart from thespirit and scope of the invention are deemed to be covered by theinvention, which is limited only by the claims which follow.

What is claimed is:
 1. Operation completion detection means for a vendsystem including one or more individually controllably operable motorsfor performing a given type of operation, said operation completiondetection means comprising power leads, vend control means includingmeans for completing a circuit across said power leads through a givenmotor, cam operated switch means associated with and connected in seriescircuit with each motor, each cam operated switch means including firstand second poles and a controllably movable contact normally inelectrical contact with said first pole and responsive to operation ofthe motor with which such cam operated switch means is associated toswitchably cycle between said poles during a complete operational cycleof such motor, said first and second poles being connected in common,and a detector circuit means having a monitor portion thereofoperatively connected in common circuit to all of such motors and theirassociated cam operated switch means and in series circuit with eachrespective motor and its associated cam operated switch means, said vendcontrol means being operable to effect the establishment of a powerdrive circuit to a given motor and its associated cam operated switchmeans and to thereby complete a motor driving circuit through said givenmotor and its associated cam operated switch means, such motor drivingcircuit initially comprising a first power circuit through said givenmotor and through the movable contact and first pole of the cam operatedswitch means associated therewith, the completion of said first powercircuit initiates operation and the commencement of an operational cycleof such given motor, operation of such given motor thereafter effectingswitchable movement of said movable contact of said associated camoperated switch means from said first pole to said second pole to breaksaid first power circuit and to establish a second power circuit throughsuch given motor and the movable contact and second pole of saidassociated cam operated switch means, whereupon said motor drivingcircuit comprises said second power circuit, further operation of suchgiven motor effecting switchable movement of said movable contact fromsaid second pole back to said first pole to break said second powercircuit and to re-establish said first power circuit through such givenmotor and through the movable contact and first pole of the cam operatedswitch means associated therewith, whereupon said motor driving circuitagain comprises said first power circuit, said switchable movement ofsaid movable contact from said second pole to said first polemomentarily interrupting the motor driving circuit through said givenmotor and its associated cam operated switch means, said momentarycircuit interruption of said motor driving circuit upon the movement ofsaid movable contact from said second to said first pole beingdetectible by said detector circuit means, said detector circuit meansresponsive to said momentary circuit interruption upon the movement ofsaid movable contact from said second to said first pole to produce ahome detection signal, said vend control means operatively connected toreceive said home detection signal and responsive thereto to effectdisestablishment of said power drive circuit to said given motor and itsassociated cam operated switch means.
 2. The operation completiondetection means of claim 1 wherein said detector circuit means includesa comparison means having a first input operatively connected to areference voltage source, a second input operatively connected to saidmonitor portion of said detector circuit means, and an output, saidcomparison means responsive to said momentary circuit interruption uponthe movement of said movable contact from said second pole to said firstpole to produce a circuit interruption detection signal at said outputof said comparison means, said home detection signal produced by saiddetector circuit means corresponding to said detection signal producedat said output of said comparison means.
 3. The operation completiondetection means of claim 1 wherein said switchable movement of saidmovable contact from said first pole to said second pole momentarilyinterrupts the motor driving circuit through said given motor and itsassociated cam operated switch means, said momentary circuitinterruption of said motor driving circuit upon the movement of saidmovable contact from said first to said second pole being detectible bysaid detector circuit means.
 4. The operation completion detection meansof claim 3 wherein said detector circuit means includes a comparisonmeans having a first input operatively connected to a reference voltagesource, a second input operatively connected to said monitor portion ofsaid detector circuit means, and an output, said comparison meansresponsive to said momentary circuit interruptions to produce circuitinterruption detection signals at said output of said comparison means,and wherein said detector circuit means further includes a signalgeneration means connected to receive said circuit interruptiondetection signals and to produce said home detection signal upon receiptof the circuit interruption detection signal effected by the momentarycircuit interruption upon the movement of said movable contact from saidsecond pole to said first pole.
 5. The operation completion detectionmeans of claim 4 wherein said signal generation means includes aflip-flop responsive to a first circuit interruption detection signaleffected by the momentary circuit interruption upon the movement of saidmovable contact from said first pole to said second pole to establish afirst output state of said flip-flop and responsive to a second circuitinterruption detection signal effected by the momentary circuitinterruption upon the movement of said movable contact from said secondpole to said first pole to establish a second output state of saidflip-flop.
 6. The operation completion detection means of claim 4wherein said vend control means includes a microprocessor operativelyconnected to receive said circuit interruption detection signals andprogrammed to be responsive to receipt of the circuit interruptiondetection signal efforted by the momentary circuit interruption upon themovement of said movable contact from said second pole to said firstpole to effect disestablishment of said power drive circuit to saidgiven motor and its associated cam operated switch means.
 7. Theoperation completion detection means of claim 3 wherein said detectorcircuit means is responsive to said momentary circuit interruptions toproduce said home detection signal only upon the movement of saidmovable contact of said associated cam operated switch means from saidsecond pole to said first pole.
 8. The operation completion detectionmeans of claim 1 wherein said detector circuit means includes a secondportion under control of said monitor portion and operable to producesaid home detection signal.